Hope your right, I don't have any Nvidia hardware anymore, definitely not any 600 series cards.

Something I wrote from our quick look at the 680 on release:

"With its Kepler architecture, NVIDIA “fixes” something that has bugged me for a while: the inability to run three monitors off of a single GPU. In fact, the company has gone one further by offering support for up to 4 monitors (a typical configuration might be 3×1 and then another monitor up top, center). Given just how powerful today’s GPUs are, it’s nice to have the option to stick to just one for multi-monitor gaming."

As far as I was aware at the time, that spanned the entire Kepler line - as long as the GPU has that many video connectors, of course. That pretty much rules out most of the low-end, but 660 and up should handle it no problem.